May 23, 2012

It's clear from both evidence and experience that NIV (aka NIPPV, CPAP, BiPAP) is very helpful for most acutely sick, dyspneic patients on a range of outcomes: symptom improvement, oxygenation, potential avoidable intubation, or preoxygenation for ETI.

However, many patients are initially resistant to NIV for a variety of reasons including:

hypoxic delirium

delirium from the disease process itself

hypercarbia

sensation of drowning, i.e. the worst sensation in the world

While some may question why patients don't always instantly welcome lifesaving therapy with open armed-compliance, it's easy to understand why someone you've never met strapping a mask to your head that blows air into your face from a big noisy machine while other people prod you with needles and place stickers and cuffs on you while monitors and vents alarm left and right on may not seem like the most comfortable situation in the world.

Over the past few years, I've developed my own habit for "maximizing patient compliance" with initial NIV, or really, how to help someone on the worst day of their life:

1) Set the mood

EM 101. Speak calmly & slowly like this seemingly crazy situation is absolutely routine for you.* Be nice to the patient. Reassure the patient that you know how terrible they feel right now, and that things will get better soon.

2) Explain that the patient is in charge

Explain nicely that while it first it may seem that the machine is blowing air in their face, after the machine figures out how they breathe, the patient drives the machine.

3) Mask only first

Put the NIV mask on the patient prior to hooking it up to the vent. If you have a friend, simultaneous symmetrical strap-tightening can help get the fit right the first time. No matter how low the settings, the vent ends up blowing some air all over the place, and that's just not comfortable. Ask any dog how that feels.

4) 0/0

Set the pressure to 0/0 and FiO2 100%. While the vent will still blow a little at first, it will really just provide fresh, clean oxygen when the patient breathes.

5) Deep breath: take the wheel

Calmly tell the patient to take some big breathes. The vent will catch on to the patient's respirations.

6) 0/2

Just a little PEEP to acclimate the patient to positive pressure...

7) ...slowly dial up

2 cm H2O of PS or PEEP at a time until at a reasonable starting pressure (e.g. 10/5 aka 15/5). I use about 10-15 seconds between dial-ups.

8) Smooth talk the patient

Some patients still need some gentle reassurance, even after a few minutes or intermittently thereafter. Sell it. Lay a gentle hand on their shoulder. Encourage them. Play some smooth jazz PRN.

*Pharamacologic Threshold*

I have a pretty high threshold to medicate patients to get them to tolerate NIV. All of these meds can cause respiratory and/or cognitive depression, and/or vomiting into a mask that forces air into their lungs.

If you are giving meds you need to be fully prepped to give an ET tube.

And, few patients need meds if you really lay on the smooth talk.

9) Consider a SMALL dose of fentanyl

Something like 12.5-25 mcg. Be gentle. Fentanyl targets air hunger and can make NIV tolerable.

10) PSA

The end of the algorithm is essentially step 1 of DSI -- ketamine or dexmedetomidine to preserve respiratory drive and airway reflexes. Like NIV in any patient, there are 2 parallel paths: potentially stave off intubation while providing ideal preoxygenation if intubation in necessary.

The caveat is that in CO2 retainers, FiO2 should be "low" to target an SpO2 around 90-92% to avoid loss of respiratory drive.** If you decide that the patient requires glottic plastic supplementation, ratchet up the FiO2 ASAP to 100% to preoxygenate & denitrogenate.

*because it is**not sure I totally buy that pathophysiology, but it looks bad if your COPD patient crumps with a sat of 100%, and it might be true.